We’re often told that the solutions to Africa’s perceived problems are to be found in “modern” and “Western” technological innovations. Traditional African knowledge is seldom even considered. When looking for answers to local food security, for example, it’s genetically modified super crops that will supposedly feed the continent’s hungry millions.
Well, here’s one example where accessible, inexpensive, indigenous African wisdom has been used in a clever way to the benefit of people and planet: the so-called fertilizer tree.
For more than 20 years, scientists have investigated the properties of Faidherbia albida, a type of acacia tree that African farmers have used for centuries, and their conclusions have been pretty amazing. This long-lived tree species extracts nitrogen from the air and transfers it to the soil via its roots and fallen leaves, where it becomes an invaluable plant nutrient.
There are, of course, many such nitrogen-fixing plants, but the Faidherbia acacia is particularly good at the job and comes with several additional benefits:
•It’s adapted to grow in an incredibly wide range of soils and climates from the tropics to deserts;
• It sheds its leaves at the beginning of the rainy season, just when food crop seeds are planted and in need of nitrogen fertilizer;
• Its leaves and pods provide a valuable source of fodder for livestock animals;
• Its bark has medicinal properties;
• It’s a source of fuel and construction wood;
•It provides windbreaks and controls erosion by reducing rain runoff; and
• It helps to mitigate climate change by trapping atmospheric carbon.
Faidherbia acacias have long been a part of traditional agricultural systems in sub-Saharan African countries from Ethiopia to Ghana and Malawi, where they are grown in the same fields as agricultural crops. Since the 1980s, scientists have been encouraging small-scale farmers to use them and similar tree species in a system that combines agroforestry with conventional seasonal crops and livestock farming. In Niger, much of the country’s millet and sorghum are grown on fields that also host up to 160 acacias per hectare.
Several studies have shown that crop yields can be doubled using this approach. In Malawi, for instance, research indicates that harvests increased by up to 280% for maize grown beneath the canopy of fertilizer trees compared to maize planted further away from the trees. Increased yields have also been observed for sorghum, groundnuts, millet and cotton.
In the last 20 years, the trees have been enthusiastically embraced by farmers in Tanzania, Malawi, Mozambique, Zimbabwe and Zambia. According to Oluyede Ajayi, a scientist at the World Agroforestry Centre and lead author of a recent paper on the subject, in these five countries alone, “there are now some 400,000 smallholder farmers using fertilizer trees to provide critically needed soil nutrients, and many report major increases in maize yields.”
It’s great to see traditional knowledge and up-to-date scientific insights combine in a sustainable agricultural system that promises to bolster soil fertility, increase crop yields and enhance local food security while providing small farmers with additional sources of income and capturing much more climate-changing carbon than most other farming methods.
Andreas is a book shop manager and freelance writer in Cape Town, South Africa. Follow him on Twitter: @Andreas_Spath
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